Wiring a new shop

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I am in the process of designing and building a new 30'x30' shop. A few questions concerning wiring have come up that I would like some input. I have read a lot of the posts about wiring but still confused on a few things.
The shop will be 30x30 with 10' ceilings, concrete floor. Power will be from a 200 amp sub panel. One man workshop with no more than one machine with exceptions, air compressor, DC, operating at a time.
A number of the machines, TS, BS, Jointer, DC, etc. will be 220.
1. Do each of these need its own dedicated circuit? How big 20 or 30 amp? Do all 220 machines operate at the same amperage or use the same plug? I have heard mention of the different plugs but don't know the difference.
2. With some of these machines situated in the middle of the floor how would you get power to them? Extension cord, ceiling drop?
3. If an extension cord is used, would placing the 220 outlets at floor level be appropriate? And placing the 110 outlets at >48"? Is there a need for placing 220 higher than ground level?
4. What size of extension cord, 12/3 or 10/3?
5. Type of wiring. 12/3 or 10/3? Would you wire the 110 with the same? Why?
I am sure there will be more questions once these get answered, thanks for your input.
Ed
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<ed louie> wrote in message

Circuits need to handle the largest load. No, 220 machines do not draw the same amperage. No, they don't necessarily use the same plugs, but plugs are not that hard to change.

Extension cords are a safety hazard. Ceiling drop can be hard to use. It just boils down to personal preference.

I would put them all at the same height. It takes real effort to get a 110 plug to fit into a 220 socket.

Depends on the length of the cord and the amperage draw. There is a table in the fine manuals.

Depends on the amperage for the 220 circuits. Just follow the code. I would wire all 110 circuits with 12/3. This would allow up to 20 amp.

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ed louie wrote: ...

If you're not using more than one at a time, then more than a couple circuits would be an absolute requirement. That said, I'd tend to over design rather than under -- it's relatively cheap extra material in the scheme of things and almost no extra labor at the same time.
Of course not...a 1hp motor doesn't draw what a 2hp motor does and certainly not everything has the same size motor.
If it's new, I'd go w/ 30A just on general principles of why limit yourself from the git-go...
Plugs are rated for current/voltage as well and prong styles are made to prevent plugging the wrong one in the wrong place.
Pick a standard outlet form factor that has the rating of the largest needed and match the cords to the outlets. The convenience of a consistent form factor in the long run far outweighs an initial conversion process imo.

If at all possible, install a raised flooring system and run power and DC there. If not feasible, overhead drops. I'm assuming from the tone this is all relatively small stuff, not the 7.5hp planer a concurrent thread is discussing...
As for extension cords for stationary machines, no!, No!, and NO!

Extension cords are for temporary use _only_ and shouldn't be necessary at all if you wire the shop adequately.
I run all handybox outlets at >48" in shop for convenience in reaching them when standing and so can occasionally do things like lean a 4x8 sheet of sheet goods against the wall w/o obstructing them. That's my personal preference and practice, if you have other reasons more overriding, go for it however you want.
In the bench areas, I make sure there are quad outlets at least every six feet. I place 220V on the basis of equipment and keep expansion in mind.

None...except for hand tools, and they can be 12.

Depends on the service...I'd go 30A for the 220 for sure, but I have stuff of the size that requires it. If you're smaller hobbyest type and don't have and don't foresee getting bigger, might get away w/ 20A service, but again, why scrimp?
20A for 110 hand tools, etc., is far less problematical, of course unless you have some sizable single-voltage motors that need more. I'd avoid them, but if you already have them and they aren't dual voltage you wouldn't want to be limited from the start...
If you haven't, do a google groups archive search -- there was a really good discussion of just this subject within the year for sure...
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For a one-man shop, 60A should be plenty. Why 200A?

Depends on the tool, but generally, no -- especially since in a one-man shop, you'll not be simultaneously using any *two* major tools. One exception is the dust collector: presumably, it will be on nearly all the time. I'd put that on a dedicated circuit. But all the other tools you named could easily share the same circuit, since only one of them will be on at a time.
The other exception is the air compressor, which also could be powered on at the same time as other tools. If you need an air compressor big enough to need 240V, put it on a dedicated circuit too.

Again, depends on the tool. You may not need even 20A for the dust collector or bandsaw. If you run 10AWG wire for all your 240V circuits, you can use 15, 20, or 30A receptacles and breakers as needed.

No.
15, 20, and 30A receptacles all have different configurations, in order to prevent plugging a 30A tool into, say, a 20A circuit. Size the circuit, and the receptacles on it, to the tools you will install.

Largely a matter of personal preference. I don't have a whole lot to say on this one, because I've never had a shop big enough for that to be an issue. I do have a 120V retractable extension cord mounted to the ceiling near the center of my shop, and that's *damned* convenient -- so based on that admittedly limited experience, ceiling drop would be my preference. Might not be yours, though.
I'm sure you'll see plenty of comments on this from others, giving the pros and cons of different methods. Consider the comments, and make your choice.

Not unless you enjoy bending and stooping. :-)

Yep. Make sure you have the *bottom* of the receptacle box at 48+", not the center.

It's kinder to your back and knees.

Depends on the tool: 12AWG is the minimum for 20A, 10AWG is the minimum for 30A.

Wire size depends on the breaker: 12AWG for 20A, 10AWG for 30A. As noted above, though, I'd run 10AWG for all of them, to enable changing a 20A circuit to 30A without having to pull new wire.
Note, though, that for 240V branch circuit wiring, you use 12/2 or 10/2, not xx/3. 240V circuits use two hots and a ground, but no neutral. Mark the white wire black or red to indicate that it's being used as a hot conductor. (A 10/3 extension cord has three conductors in it, black, white, and green; 10/3 nonmetallic cable has *four* conductors, black, red, white, and bare. You only need three.)

Yep -- that is, using 10/2 or 12/2 as appropriate, not xx/3.

Because that's what's needed.
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Doug Miller (alphageek at milmac dot com)
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<<<<<<<<<< SNIPPAGE >>>>>>>>>

60A??? I could use almost that much just for lighting. :-)
Wayne
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60A @ 240V = 14.4KW = 3,600 standard 48" fluorescent tubes.
Atsa lotsa lights!
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Doug Miller (alphageek at milmac dot com)
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Doug Miller wrote:

Not many shadows, one would presume?
Eliminates need for space heating in the winter, too, as a bonus!
:)
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Yah, but what about the A/C bills in the summer? :-b
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Doug Miller (alphageek at milmac dot com)
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I'll share my thoughts on the things I know about (no idea about your localised extention gauges or plug styles).
You're unlikely to get single phase machines that draw substantially more than 10A. Most will draw less. My shop is wired 20A 240V on two circuits. Circuit breakers are thermal as well as overload type, and I've not had a problem with them tripping, ever. On very rare occasions I have 2 big machines running and 1 small (RAS, planer, compressor/extractor)- usually only 1big, 1 small. Only time those breakers tripped was when I tried to continuously run a single phase welder on a hot day. (the welding took place outside the shop, on the drive, b.t.w!)
I have 1 ceiling drop, for handheld tools at the assembly table and use extention cord for my over-and-under which gets moved around. Both have their disadvantages.
Personally I wouldn't put the outlets in a workshop too low. Think back-pain. Think sawdust. Think spillages. I'll have mine so I don't need to bend over to get at them, thanks. Speeds things up, too.
-P.
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Peter Huebner wrote: ...

http://www.powermatic.com/shop/index.cfm?navPage=4&iid 737&tabtails
All you need is $$$! :) I personally would be lost w/o mine...
Somehow I suspect OP doesn't, though... :) Even then, I'd still definitely recommend going w/ 30A on a new shop -- just seems cutting corners where incremental cost just isn't that much.
Again, of course, imo, ymmv, $0.02, etc., etc., ...
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Hi Ed,
New shop? Good for you! Are you planning to stay there long?
If so I'd put a minimum four 120V 15A and two 240V 20A receptacles every 15 feet all around the inside walls, each drop on its own circuit. Install air and dust collector drops at the same time. Put some power, air and DC receptacles in the ceiling. Put lights on their own circuit. Install retractable power and air cord reels. Install a dedicated circuit for your DC and air compressor.
Plan where you are going to put your table saw and work table. If in the middle of the room then install a couple of 4" conduits into the floor.
Personally I prefer shop receptacles at 48" off the ground.
Spend money and insulate the shop well. Put in a good heating/cooling/air make up system.
For a good shop I recommend to spend a little more now or end up paying a lot more later.
Mike
<ed louie> wrote in message

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What he said. 30 X 30 leaves a lot of space that's a long ways from a wall. Cords hung from the ceiling get in the way more than you think. Put a couple of runs of conduit under the slab with long-radius elbows and couplings that are capped off flush with the floor. If the layout changes, the conduit won't be a tripping hazzard. I ran flexible conduit carrying both 220 and 110 from the floor fitting to my tablesaw. The 110 is wired to a receptacle on my tablesaw extension to run the router or whatever else I need out in the middle of the floor. For the small investment in conduit, the payoff in safety and convenience is big.
DonkeyHody "In theory, theory and practice are the same, but in practice, they are not."
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Lights on dedicated circuit is a great idea. It stinks having the lights go off because something poped the circuit.
I did 20 amp circuits in my house using 12 guage wire. The air compressor and the vacuum cleaner in the garage on the same breaker sometimes pops when bead blasting.
Circuit size of 220 is dictated by equipment. Your big air compressor might spec a bigger circuit than the table saw.
On Sun, 15 Jul 2007 20:50:14 -0500, "Epictitus"

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On Jul 15, 4:42?pm, ed louie wrote: Ed
Lots of nice information so far. So here comes mine.
I am in the sunbelt so am well insulated (12"), 12" walls and ceiling. Steel studs and framing, Air Conditioned, no need for heat. Shop temp rises 3 degrees on a 100 degree day with the air off.
Windows, (double pane) and door on the north side. Other 3 walls have shelving from floor to ceiling. (Costco)
Electric is from main house panel. 60 Amp 220 volts and a 20 amp emergency circuit should I trip any breakers on the subpanel in the shop. Emergency circuit feeds a 20 amp outlet and a light which comes on with loss of either side of the 60 amp 220 circuit.
Subpanel in the shop is a Square D 125 Amp panel that has 8 single spaces or 16 ? spaces. Remember the neutral does not get grounded on a subpanel. I also have a 10' ground rod for the ground at the shop.
I have my lathe, Air Compresser and AC on 220 circuits with 2 spare 220 breakers. All 220 is wired with #10 wire. All other wiring is #12. I have 8 light switches in 2 metal boxes on the wall adjacent to the door. Also a 12" X 12" electrical box for any spill over connections that tend to clutter the subpanel. And a separate 4X4 box for the emergency light and outlet. The box is large enough for the relay that monitors the 220 legs from the house service panel.
All my 220 outlets are in the same box with a 110 outlet. All outlets are the 20 amp type. 110 & 220. And all the outlet boxes are deep 4" X 4" metal boxes with mounting brackets that attach the boxes to steel studs.
My Air Comprersser is 220 volts. I turn it on with its' breaker as needed but intend to put in a relay that is controlled by the main lighting switch. This will keep it from cycling when I am not in the shop.
All my lighting is on 15 amp circuits. Everything else on 20 amp circuits. Remember circuit breakers are for the protection of the wiring only.
I have cable TV, phone, intercom, remote swithching for the AC and anything else I can think of including an alarm and the outside light so I can see in the dark coming and going. The shop is 10 feet below the house. I can see the roof from the back porch. There are 2 condutits from the house. Power and everything else. 1?" and 1". Should I have to do it over both would be 2".
Get everything you can on 220 volts. It will ease your electrical problems. Don't buy cheap electrical outlets. Get the specification grade at least. Buy wiring by the coil. 250' for # 10 and 500' for #12.
My AC is the split type. The remote compressor/fan on the outside in the shade and the coil and fan on the ceiling at the back of the 20 X 20 shop.
Hope this helps Bob AZ
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wrote:

I'm planning something similar.
So you put a 60 amp breaker in the main (house) panel and ran a circuit to the subpanel. Did you pull the 125 main breaker from your subpanel and put a 60 amp main in the sub?
what feed did you use. #4/3 wg Type SER or individual # 6 THWN wires in conduit with a # 10 ground? Or did you go oversize from the minimum required to carry 60 amps. Did you cost the difference between SER and conduit. Did you have to go underground or all above?
Why the extra ground rod? Does the code require it? The sub ground bus is tied back to the main panel ground bus with the subpanel bonded to the ground bus but not strapped to the nuetral bus, I assume.
FRank
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Frank
The NEC allows a 60 amp feed from the house or another sub panel, to feed directly to the additional subpanel buss without using a main breaker in the additional subpanel. The 125 amp panel comes without a main breaker. Home Depot. I used #6 THHN wire. 2 hot legs, 1 neutral and a ground from the house panel. #6 is oversize but I always go oversize on the feed to any panel. This was an underground run, 85'.
The extra ground rod is not required by code. I did it for lightning protection. I would lose lots of things without it since we have nasty lightning every summer. The #6 ground back to the main panel is required and would be wiped out ion a lightning strike every summer. Thus the ground rod. There is no wire size that will take a lightning strike of any intensity.
Where I live we have soil conditions such that one goes PVC conduit or else. Even EMT conduit eventually disappears due to electrolysis. I know it sounds funny but just this last week a friend had to start replacing a service to his shop that was in EMT conduit. And direct burial is nice but requires a 12" sand barrier. Thus PVC conduit is the less exensive way to go. Costs a bit less and lasts forever. I don't use Al wire at all. Too many longterm problems. The power company has my house fed, underground, with AL and they will eventually have to replace it. The neutral usually burns in two. I knew PVC underground was cheaper and while the man was preparing my site for the slab he just took another hour to dig the electric trench. I had the conduit ready to drop in and he covered it up in about 2 minutes with clean fill. We have lots of rocks that move around a lot. Under certain conditions the NEC requires a ground the size of the current carrying conductors or larger. With what I know now I would go even larger. It was not much more money. I probably spent less than $100.00 for all the electric add ons. It is cheap insurance. And I had less to worry about for all the other things like cable TV, intercom, computer etc.
Take care Bob AZ
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wrote:

Thanks, useful information. My shop, although a completely separate building, is attached to the house, in theory, as a breezeway offers a protected run without having to make the choice between direct burial or conduit type. Think I will put a main breaker in my subpanel though.
Better check that NEC. My understanding is if it is a completely separate building and has over six spaces it's required. But I never checked it, going by an article I read in Fine Hombuilding (April 2003)
Frank
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On Jul 16,

The 60 Amp breaker feeding a subpanel is an exception according to the city permit folks. I know the inspector checked the 60 amp thing. I watched him do this.
But beware. Not all municipalities always follow all the code all the time.
A little background. Goes something like this. Years ago when 50 amp was a big panel they went to 100 amp. But the biggest branch circuit breaker that would fit in the panel was 60 amp. So they allowed 60 amp branch circuits to power a sub panel. And there was no max on the subpanel as long as it was fed by a 60 amp breaker. Thus the provision to allow a sub panel to be fed by a 60 amp breaker with no main in the sub panel. So using a bigger subpanel gives some options for lots of separate breakers/circuits in a shop like yours and mine.
Bob AZ
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Somebody wrote:
> The NEC allows a 60 amp feed from the house or another sub panel, to > feed directly to the additional subpanel buss without using a main > breaker in the additional subpanel. The 125 amp panel comes without a > main breaker.
Be careful, the "six hand rule" applies.
IOW, all power must be disconnected with a maximum of six motions of the hand.
Install a 2P-60 as a branch c'bkr in the main panel.
Upgrade the PVC conduit size at least one size, maybe two.
Conduit is cheap, straining your back isn't.
Install a 125 MLO, 12/24 surface mount panel in shop(12-1" or 24, 1/2" branch spaces).
Add a 2p-60A main c'bkr kit along with an insulated ground bus bar since this is a sub panel.
Use 1P-20 c'bkrs for all 120V circuits of which at least 4 are dedicated to lighting.
240V circuits:
Dedicate a 2P-50 for a 5HP air compressor
2P-30 for the balance.
Run every thing you can at 240V, especially stationary tools like DC, TS, Jointer, dedicating an individual c'bkr for each load.
Use 30A locking receptacles & plugs for 240V services.
You do the above, the inspector will smile and give you your permit.
Lost count of how many of the above packages I sold over the years, but it was a bunch.
Lew
PS: Wire all your receptacles in 4" (2 gang) boxes.
Makes life a LOT easier.
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Lew Hodgett wrote:
Now I'm no pro, but it seems like some of these suggestions are overkill.

Why? I could see two for safety, but four? And why bother making the lighting circuits 20A, when they won't be drawing anywhere close to 15A?

Sounds reasonable. I didn't in my small shop, but only because I don't have room for a big compressor. I have a spare 30A circuit available for a future compressor upgrade.

This seems like overkill, since its generally only needed for 5HP motors. Given the price of copper around here, I couldn't justify it.

The individual circuits won't hurt, but it's probably overkill. In a small shop the stationary tools likely won't ever run simultaneously (and with only 60A supply, there isn't the juice for it anyways). It makes sense to have DC and compressor on individual circuits, the rest likely won't be an issue. I split mine over multiple circuits because I had the cable, but its likely not necessary.

This would require replacing the plugs on the tools. If you're using overhead drops it makes sense, but for wall or floor I don't see major benefits. I've never pulled out a cord accidentally on a stationary tool.
Chris
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